Rusty Blackbird - Bob Duchesne

By RANDY LEE LOFTIS / The Dallas Morning News
rloftis@dallasnews.com, 12:00 AM CST on Sunday, February 7, 2010   From North Texas to Florida, a high-pitched voice is strangely missing from the chatter of wintering birds. The rusty blackbird, a winter visitor to Dallas-Fort Worth, has suffered one of North America’s steepest and least understood declines. Since 1970, scientists say, its numbers have plunged 85 percent to 99 percent. Experts have a lineup of suspects, including habitat changes, disease, climate change and mercury pollution. But they have no proof of what has pushed Euphagus carolinus toward an ecological brink here and across the continent. … Many common North American migratory birds have lost 60 percent or more of their numbers since 1967, according to the National Audubon Society. They include North Texas species such as the northern bobwhite, northern pintail and eastern meadowlark, each down more than 70 percent. Even so, the rusty’s plight stands out. “This loss is way out of proportion to other blackbirds,” said the Smithsonian’s Greenberg. Some species adapt easily to farms, suburbs and malls, but others have a tough time if their particular habitats become scarcer. The rusty isn’t the pickiest, but it does prefer a watery home. It breeds in summer in wetlands in Canada and Alaska. Rusties seek similar places when they head south for the winter, favoring wetlands from the Atlantic to North Texas. Their biggest winter concentration appears to be in Mississippi. … Very few rusty blackbirds show up west of Fort Worth, according to www.eBird.org, an online bird observation site. The land is simply too dry. … In Texas, the trend is grim: numbers off a cliff since 1960. “The bird’s population has fallen through the floor in a real abrupt manner,” Arvin said. “No one knows the reason why.” Habitat loss is an unproven possibility. The Boreal Forest, the great northern woodland that rings the globe across northern Canada, Alaska and Russia, has seen logging and development, but vast breeding areas remain. Wetland loss in the winter range has been dramatic, but scientists can’t lay all the blame there. Other explanations include climate-related habitat changes. Northern latitudes, where the bird breeds, are perhaps most vulnerable; still, there’s no proof that an altered climate is responsible. Mercury from coal-burning power plants is also possible. Researchers have found high levels in red-winged blackbirds, which often share wetlands with rusties. …

Climate change, pollution are suspects in rusty blackbirds’ plummeting numbers via Apocadocs